Automatic arc welding apparatus and control therefor



AUTOMATIC ARC vQE. MANN 2,294,312

WELDING'APPARATUS AND CONTROL THEREFOR Filed Aug. 24, 1940 ,60 Switch closd at ;X//end of e ach welding operatlon.

Inventor: Vernon E. arm,

His Acbovney.

Patented Aug. 25, 1942 AUTOMATIC WELDING APPARATUS AND CONTROL THEREFOR Vernon E. Mann, Scotia, N. Y., asalgnor to General Electric Company, a corporation of New York Application August 24, 1940, Serial No. 354,129

7 Claims.

by means of which welding current is supplied thereto. These electrodes are frequently referred to as stick electrodes. Automatic arc welding machines have been devised for feeding these electrodes in order to avoid the complications resulting from providing means for supplying welding current through the flux coatings of electrodes of indefinite length which are furnished to the trade in coils or on reels. Such automatic.

machines also avoid the use of heavy coated electrodes of special types which have heretofore been proposed for use in automatic arc welding machines and, consequently, make it possible to use in an automatic machinethe same'supply of stick electrodes that are used for hand welding operations.

Where the same welding operation is repeated,

any arrangement which enables the welding operator quickly to inserta new standard length electrode in the machineor which increases the total time available for welding is of considerable value to the manufacturer in that it enables a tance such that a new electrode is properly positioned therein when its end rests upon the work but which is also spaced from the electrode feeding means a sufficient distance for travel of the holder away from the work for are striking purposes under control of this electrode feeding means. This decreases the total welding time in that it is only necessary to withdraw the electrade from the work to strike the welding are.

7 Itis another object of my invention to provide an automatic arc welding machine of the stick feeding type in which a limit switch control which is responsive to the position of the electrode holder and the position of the work after each welding operationis employed for returning the electrode holder to its loading position when the amount of unconsumed electrode'is' insuilicient for another welding operation. Cer- *tain welding operations must be completed by one uninterrupted line of welding in order to avoid'porosity where welds from two different electrodes join or to insure a, desired appearance thereof.

greater production within a limited period of time. It is also of great value to remove from the judgment of an operator his estimation of whether the remaining portion of a partially consumed electrode is of sumcient length to complete another welding operation before reloading the machine with anew electrode.

It is an object of my invention to provide an automatic arc welding machine or an attachment for lightly coated or bare wire automatic arc welding heads bywhich these desired results are obtained.

It is also an object of my invention to provide an automatic arc welding machine of the stick feeding type in which the loading position of the electrode issuch that a new electrode may be properly inserted therein without requiring the careful attention of the welding operator.

It is a further object of my invention to provide an automatic arcwelding machine of the stick feeding type in which the electrode holder is returnedto a loading position which is not In the drawing Fig. 1 is a diagrammatic view illustrating one embodiment of my invention and vFig. 2 is a sectional'view illustrating a fluid operated stop which may be associated with the mechanism for returning the electrode holder to its loading position as a substitute for the stop and spring biased plunger shown inFig. 1.

In the arrangement illustrated in Fig. 1, an electrode holder and the standard length electrode therein are fed away from and toward the work to strike and maintain a welding are by means of an electrode feeding means which is adapted to engage a feed rod attached to and forming a part of the holder. .The connection between the electrode feeding means and the feed rod of the holder is controlled by a fluid operated means. Fluid operated means are also provided for returning the electrode holder to its loading position. These fluid operated means are controlled in response to the position of the electrode holder and the position of the work after a welding operation to return the electrode holder to its welding position when, at the end of a welding operation, the consumption of an electrode in the holder exceeds a predetermined amount such that the portion of the partly consumed electrode remaining in the holder is lnsufllcient for making the next weld. Both of these fluid only spaced from the work a predetermined dis- 5:; operated means are energized and deenergized at the same time. When deenergized, the oper 'ating' inertia of the fluid operated means which controls theconnection between the electrode feeding means andthe feedrod of the holder, 3

permits a spring biased plunger located between the holder and a stop to position the-holder from this. stop against which it was moved by the other fluid operated. means and thus locate it in its loading position. This loading position is so spaced from the work that a new standard length electrode is properly positioned in the holder when its arcing terminal restsupon-the work and so spaced from the electrode feeding means that there. is suflicient distance for-travel of the holder away from the work for arc striking purposes under the control of the electrode feeding means.

In the modification shown in Fig. 2, the return movement of the electrode holder is arrested by a fluid operated stop which when deenergized releases the electrode holder for further-movemer t away from the work for arc striking purposes under the control or the electrode feeding means associated therewith.- Inthe arrangement shown in Fig. 1, the bared 'end portion of a standard length electrode i9 is properlypositioned in an electrode holder H when its arcing end rests against the work l2. 7

This electrode holder comprises a body portion I3 against which the electrode is held by a movable jaw ll pivotally attached thereto and forced into engagement with the electrode by a. cam

- latch l5 mounted on the body portion of the holder. The lower end of electrode l is properly positioned relatively to the work by a guide 16 whichjs mountedon the holder by a member 11. Welding current is supplied to the holder through a conductor 18 which is attached to the body 13' thereof. The electrode holder and the .electrodethere in is fed away 1mm and toward the-work bya.

pair of iced rolls 1! and 29 which are adapted to engage a feed rod 2| forming part 01 theholder'.

head may have the construction more fully illustrated in United States Letters Patent 2,024,965,

Verni J. Chapman, granted December 17, 1935.

and assigned to the assigneeof this invention.

The speed and direction of rotation'or the feed motoroi the welding head andconsequently the speed and direction of rotation or feed roll I9 may be controlled through the-agency of any .suitable are responsive system such as shown in United States LettersrPatent 1,701,372, Frank M.

Jeits, granted February 5,- 1929, or United States Letters Patent 2,175,017, William D. Cockrell, granted October 3, 1939, both of which are assigned to the assignee of this invention. As

shown in Fig. 1, .ieed roll 20 is positively driven by feed roll "through intermeshing gears 23 and 24.

Feed rod 2| '0! the .electrode holder passesthrough and is guided by asupport member 25 which is attached to the housing 22 of the welding head. The upper end or this feed rod is enclosed withina guide tube 29 whose lower end is mounted in a holder 21 forming part of the housing 22' 01 the welding head.

The electrode holder is returned from the position it assumes due to electrode consumption to a loading position for a new'electrode'through the agency or a fluid operated means 23.

fluid operated means comprisesa cylinder 29 the lower end of which is mounted on and is closed by support member 25 and the upper end of which a is closed by a cap 39 having a vent- 3| therein.

Fluid such as air is supplied and exhausted \from the lower-end of this cylinder through a conduit 32 which 'passes through support 25 into the lower portion of cylinder 29. A piston 33 located within cylinder 29 is connectedby a piston'rod 34 to an arm 35 forming part of electrode-holder.

l I. A suitable packing'is providedbetween this piston rod and support-25 to' prevent escape of 1 conduit 32.

- inder 29, piston 33 and electrode holder H are moved away from the work until the holder e'nport, consequently, functions as'a stop in the path of travel-of the electrode holder.

. an exhaustconnection is completed from cylinder 29 through conduit 32, the electrode holder support :by a plunger 36 which is mounted in 25 arm 35 of the holder and biased by. a spring'3l to.

the% position illustrated. This spring biased plunger locates-the electrodeholder relative to the welding head in its loading position which is not only spaced from the work apredetermined distance such that a new standard length elec-.

trode is properly positioned therein when its end rests upon the work but which also spaced from the welding head a suificient distance .ior. travel of the holder away'from the work for are striking purposes under the control of feed rolls I9, and 20 of the welding head.

Feed roll 20;. its driving gear 26 and the axle connecting them, are mounted in-oneend of-ablockr38 whose other end is connected by a piston 4 rod 39 to a piston 40 forming part oi a fluid operated means II which functions to move feed roll 20 into and'out of driving engagement with sure, such as air, is supplied to or exhausted from the sidelof piston 40 opposite spring 43 through a conduit 46. A-packing between piston rod 39 and the 'end wall of cylinder 42 through which this piston rod extends prevents loss of pressure fluid'between these members. a 4 Conduits -32 and 46 are connected by a common conduit 41 which branches into conduits l3 and 49. Conduit 48 is connected through a valve 50 to a source of fluid pressure and conduit I9 is connected through a valve 5| for exhaust to atmosphere. .The operation of valves 50 and 5| simultaneously establish pressure and exhaust connections for energizing and deenergizing fluid operated means 29 and lb 'When fluid operated 05 means 28 is energized, it moves the electrod holdor away from the work into engagementwith support 25 and when fluid operated means 4| is energized it .moves the feed roll 29 out of engagemerit with feed rod 2| of the electrode holder. 'When these fluid operated means are deenergized, spring 43 of fluid operated means ll again forces feed roll.20 into engagement with the feed rod of the holder. Due to the operating inertia of the pressure fluid suppliedto cylinder 29 through When. fluid under pressure is supplied to cylgages support 25 on the welding head. This sup-1 When is moved a predetermined distance away from of this invention.

until after spring biased plunger fl has moved the'holder' a predetermined distance from support 25 into its loading position. This loading position, as previously noted, is notonly spaced from the work a. predetermined distance such that a new electrode is properly positioned theretype and are provided with operating windings 52 and 53. These vn'ndings are selectabl'y connected across a source of supply through contacts 55 of a relay 56. This relay is provided with an operating winding 51.. The connection of this winding across the source of supply 54 is controlled by limit switches 58, 59 and Y61!. A holding circuit for this relay is established through limit switch 58 andcontacts 6| of this relay.

Limit switches 56 and 59 are operated in response to predetermined positions of the electrode holder. They are mounted on tube 26 through which feed rod of the holder passes. Limit switch 58 is mounted at the top of this tube and so positioned thereon that when holder H engages or is about to engage support 25, feed rod 2| operates it to open its normally closed contacts. Limit. switch 59 is supported on the lower portion of tube 26, a part of which is cut away to expose feed rod 2| located therein. When this feed rod passes below limit switch 59, it closes its normally open contacts.

Limit switch 60 is responsive to the position of the work I2 after each welding operation. Its contacts are closed by a cam disc 62 after each away from this loading position toward the work in order to facilitate illustration of this plunger and its support in the electrode holder.

Assuming that the electrode holder is in its loading position, one end of a standard length stick electrode 16 is properly positioned therein when its other end rests upon the work l2. Consequently, the loading operation consists merely in placing one end of electrode l0 upon the work I2 and its. other end in electrode holder II and then operating cam latch l5 to close the holder welding operation has been completed. A connection 63 is provided between cam disc 62 and the work holder and traversing means 6|. This connection is such that one complete revolution is imparted to cam disc 62 for each welding operation. Thus, it the weld on work I2 is lapped open itself a predetermined amount, connection 62 is such that cam disc 62 makes one complete a suitable mechanism such as a ratchet drive may be provided in connection 63 so that cam disc 62 is not also reversed with the reversal of work traversing means 64.

The work traversing means 63 may be a turntable for supporting the float valve chamber of a refrigerator. This turntable and its drive may have the physical structure described and claimed in United States Letters Patent 2,280,627, Verni J. Chapman, granted April 21, 1942, and assigned to. the assignee of this invention. Any suitable traversing control may be provided for the work traversing means 64. A suitable control has been described and claimed in my application Serial No. 351,979, for Automatic arc welding systems, filed August 9, 1940, andas'signed to the assignee The operation of the welding hea d and its structure above described is as follows:

In the drawing the electrode holder has not been illustrated in its loading position which would be determined by the action of spring biased plunger 36 and support 25. It has been moved and clamp the electrode therein.

The welding operation is then initiated by operating a start button such as shown in the above referred to Letters Patent to Frank M. Jefts. The are responsive control associated with the welding head will thereupon impart rotation to feed rolls l9 and 20 to move the electrode holder away from the work to strike an arc. The spacing of holder II from support 25 by spring biased plunger 36 makes possible this are striking operation under the control of the electrode feeding means. After an arc has been established between the electrode and the work, feed rolls l9 and 20 of the welding head will thereafter move the electrode holder toward the work to compensate for the consumption of the electrode located therein and maintain an arc of predetermined voltage. When the welding operation has been completed, the operator may stop the welding operation by closing a stop switch such as shown in the above referred to Letters Patent to Frank M. JeftS. This stopping may, however, be made automatically by a travel control such as disclosed in my abovereferred to application.

If the electrode is of suflicient length to perform more than one welding operation, the operator initiates other welding operations until finally the end of feed rod 2| of the electrode holder passes beyond limit switch 59. Then at the end of a welding operation when limit switch 66 also closes,- the operating winding of relay 56 is connected across the source of supply 54 through limit switches 60, 59 and 58. This relay consequently closes its contacts 6| and transfers the. connection through its lower contacts 55 to its upper contacts 55.- The connection established through contacts 6| completes through limit switch 58 a holding circuit for the operating winding 51 of relay 56. The closure of the upper pair of contacts 55 of relay 56 connects the operating windin 52 of valve '56 across the source of supply 54. Fluid pressure is consequently supplied to the fluid operated means 26 and 4|. j

Fluid operated means 4| disengages the connection between feed rolls I9 and 26 and feed rod 2| of the electrode holder and fluid operated means 28 moves this electrode holder away from the work until it engages support 25 which acts as a stop. Opening 3| in capfilof cylinder 29 of fluid operatedmeans 29 cushions this return movement by limiting the rate at which air is exhausted from the upper end of the cylinder.

When or just prior to the time that the electrode holder engages stop 25, limit witch is is 53 of exhaust valve 5| across the source of sup-' ply 56. The operation of this valve deenergizes the fluid operated means 26 and 4| by connecting part ofthe fluid operated means 4| is moving feed roll 20 into engagement with feed rod 2|. spring biased plunger 36 moves the electrode holder to its loading position. The holder is consequently properly positioned for the insertion of a new electrode in themanner above described.

The return movement of the electrode holder may be arrested by a fluid operated stop such as shown in Fig. 2. in order properly to locate it in the desired loading position. This fluid operated stop will replace thespring biased plunger 36, of Fig. 1. It will be associated with the fluid operatedmeans 213,v corresponding parts of which have been indicated by corresponding reference numerals in Fig. 2 where the fluid operated means (as a whole has been identified as 28'.

. them to exhaust. While the spring 43 form:

ing stick' electrodes. In either case. my inven-.' tion is not limited in its applicationto the feeda ing of heavy coated stick electrodes but maybe used for ieeding any form of short length electrode.

Under some circumstances a niore positive drive between the feedrolls and feed rod of the holder may be required. If so; a rack may be formed in or attached to the feed rod opposite As shown in Fig. 2, one end of this fluid operated stop 33' engages the piston 33 within cylinder 29 and its other end is connected to a piston 65 which islocated within a cylinder 66 supported on the upper end of cylinder 29. Conduit 32 branches to supply fluid to the upper portion of cylinder 68 as well as to the lower portion of cylinder 28. Consequently, when fluid operated means 28' is energized, piston is moved upward in cylinder 29 until it engages stop 33' which has been moved to the position illustrated in Fig. 2 by the supply of fluid to cylihder 38. It is to be noted that cylinder 68 is of largerdiameter than cylinder 29, and consequently the totalpressure on piston 65 white greater than the total pressure onpiston 33 so that when piston 33 engages stop 36', its upward movement is arrested thereby. When fluid opfeed roll which will beprovidedwith gear teeth "that mesh with and drive the rack. ,Other forms ofdrive more positive than the friction drive a above illustrated will occur to those skilled in the art to which my invention relates.-

When the feed rodis provided with a-ra'ck, limit switches 58 and 59may be repositioned on tube 28 so that they engage an,even portion of the feed rod. By substituting elongated shoes afl'ected by the irregularities of the feed rod resulting from the teeth of the rack.

It is, of course, apparent that many variations and modifications may be made 'of my invention without departing from its spirit and scope Thus, while. I have shown particular embodi-' ments thereof, such modifications and variations are contemplated as fall within the true spirit and scope of my invention as defined in the appended claims.

erated means 28 is deenergized by connecting conduit 32 to exhaust, stop 38 will no longer vprevent further upward movement of piston 33 and the electrode feeding mechanism may consequently function to move the electrode holder away from the work to strike the welding arc.

When using the fluid operated means 23' shown in Fig. 2 in place of the'fluid operatedmeans 28 of Fig-1, it-is, of course-apparent that limit switch 58 must be properly located on tube 28 so that it. is operated by feed rod 2l when or'just prior to the time that piston 33 engages stop 36'. Otherwisethe substitution of fluid op- 'erated means 23' of Fig. 2 for fluid operated means 28 of 1 requires no other change in the arrangement of Fig. 1 above described.

1 In both the arrangements of Fig. 1 and Fig.

2 it mayprove desirable to have conduit 32 or smaller size than conduit I so that fluid operated means ll disengages ieed rolls I! and 20 from feed rod 2| before fluid operated means '23 operates to move .the electrode holder and feedrod'2l. away from the work. If this is not done, fluid operated means 28 may be stalled I so thatpre'ssure is built up in its operating cylinder before feed-rolls l3 and "disen age and release'feed rod 2| resulting in a return 'move-' 'Jment or the electrode holder which is initiated with a jerk due to this built up pressure. Conduits 32 and '46 may be of the same size and a restriction or choke placed in conduit 32 to accomplish this result.

What I claim asnew and 'desire to secure by Letters Patent of the United States is: 1. Welding. apparatus comprising an electrode holder, a welding head having feeding means for moving said electrode holder away from and toward the work to strike and maintain a welding arc of predetermined length between the work and a standard length electrode in-said electrodeholder, means for controlling the driving. connec-' tion between 'said'electrode holder and said feeding means of said welding head, means for moving said electrode holder away from the work to a loading position spaced from the end of its travel away from the work by a distance at least equal to the. are striking movementaway from the work imparted thereto by said feeding means of said welding head, means for operating said controlling means and said moving means to dis- 1 engage the driving connection between said elec-: trode holder and ,said feeding means of said weldinghead, move said electrode holder to its. said leading position and re-establish the driving connection between said electrode holder and said feeding means of said welding head, means forinitiating the operation of 'said last men-- said work holder.

2. Welding apparatus-comprising an electrodq holder, a feed rod attached to said holder, electrode feeding means for moving said feed rod away from and toward; the work to strike and. I maintain a welding are between the work and an which are adapted for'feeding bare or lightly,

coated electrodes of indefinite length. It may, however. be an integral part of an automatic are welding head which is solely for feedit electrode in saidholder, fluid operated means which when energized moves. said holder away from the work, means including a stop and'a spring biased plunger located between said holder and said stop for'limiting'the travel imparted to said holder by said fluid operated means and for spacing, said holder from said stop a predetermined distance suificientfor are striking movement after said fluid operated means has been gagement for an interval of time suflicient for' said stop and said spring biased plunger to space said holder said predetermined distance, and fluid control means for energizing and deene'rgizing,

said fluid operated means.

3. Welding apparatus comprising an electrode holder, a feed rod attached to said holder, electrode feeding means for moving said feed rod away from and toward the work to strik and maintain a welding are between the work and a standard length electrode in said holder, means for establishing a connection between said feed rod and said electrode feeding means, fluid operated means which when energized disengages the connection between said electrode feeding means and said feed rod, a second fluid operated means which when energized moves said holder away from the work, a third fluid operated means which when energized limits the travel imparted to said "holder by said second fluid operated means and locates it in a loading position which is spaced from the work a predetermined distance such that a new electrode of the same standard length is properly positioned in said holder when its end rests upon the work-and which when thus reloaded isalso spaced from said electrode feeding means a sufficient distance 'for travel of said holder -away from the work for are striking purposes under the control of said feeding means.

and means for energizing anddeenergizing sai'i fluid operated means.

4. Welding apparatus comprising an electrode holder, means for feeding said electrode holder toward and away from the work to strike and maintain a welding are andfor returning said electrode holder to a loading position, and means including a limit switch responsive to the spacing of said electrode holder from the work and a second limit switch responsive to the position of the work at the end of a welding operation for including a limit switch responsive to a predetermined travel of said holder away from the work for operating said valve ,controlling' means- .to deenergize said fluid operated means. 6. Welding apparatus comprising an electrode holder, a feed rod attached to said holder, electrode feeding means for moving said feed rod away from and toward the work to strike and maintain a welding are between the work and a standard length electrode in said holder, fluid operated means for controlling the. connection between said electrode feeding means and said feed rod, fluid operated means for returning said holder from the position it assumes after a welding operation due to electrode consumption to a loading position which is spaced from the work a predetermined distance such that a new electrode of the same standard length is properly p0sitioned therein when its end rests upon the work and which whenthus reloaded is also spaced from said electrode feeding means a sufficient distance for travel of said holder away from the work for arc striking purposes under the control of said electrode feeding means, and means including a limit switch responsive to a predetermined travel of said holder'toward the work, a limit switch responsive to a predetermined travel of said holder away from the work and a limit switch responsive to the position of the Work at the end of a welding-operation for controlling the supply of pressure fluid to said fluid operated means to return said holder to its loading position and disengage the connection between said electrodefeeding means and said feed rod during the return of said holder to its loading position.

7. Welding apparatus comprising means for clamping one end of a stick electrode, a feed rod attached to said clamping means, electrode feeding means for moving said feed rod away from and toward the work to strike and maintain a welding are between the other end of said electrode and the work, means for establishing a connection between said feed rod and said electrode feeding means, fluid operated means which when energized disengages the connection between said electrode feeding means and said feed rod, fluid operating said last mentioned means to returnsaid electrode holder to its loading position when at the end of a welding operation the consumption of an electrode in said electrode holder exceeds a predetermined amount.

5. Welding apparatus comprising an electrode holder, a feed rod attached to said holder, electrode feeding means for moving said feed rod operated means which when energized moves said clamping means away from the work, fluid operated means which when energized limits the travel imparted to saidclamping means by said fluid operated means and positions said clamping means in a loading position which is spaced from V the work a predetermined distance such that one awayfrom and toward the work to strik and maintain a welding are between the work and an electrode in said holder, means for establishing a connection between said feed rod and said electrode feeding means, fluid operatedmeans which when energized disengages the connection between said electrode feeding means and said feed rod, fluid operated means which when energized moves said holdera predetermined distance away from the work, electrically operated valve means for controlling the pressure and exhaust connections and consequently the energization and 'deenergization of said fluid operated means, means including a limit switch responsive to a predetermined travel of said holder toward the work and a limitswit'ch responsive to the position of the work at the end of a welding operation for operating said valve controlling means to energize said fluid operated means, and means 75" end of a new electrode is properly Positioned therein when its other end rests upon the work and which is also spaced from said electrode feeding means a suiiicient distance for travel of said clamping means away from the work for are striking purposes under the control of said feeding means, electrically operated valve means for I controlling the pressure and exhaust connections and consequently the energization and deenergbzation of said fluid operated means, means including a limit switch responsive to a predetermined travel of said clamping means toward the work and a limit switch responsive to the position of the work at theend of a welding operation for operating said valve controlling means to energize said fluid operated means, and means including a limit switch responsive to a predetermined travel of said clamping means away from the work for operating said valve controlling means to deenergize' said fluid operated means.

VERNON E. MANN. 

